If the maximal power output of a microwave power supply is upgraded, the working temperature of the transformer in the microwave power supply will usually be higher because it accumulates more heat. It is crucial to dissipate the more accumulated heat for maintaining the transformer in an appropriate working temperature. The maximal power output of a microwave power supply is proportional to the volume of the transformer, while the heat-dissipating ability is proportion to the surface area of the transformer. Therefore, the ratio of maximal power output to heat-dissipating ability is equal to the ratio of volume to surface area of the transformer and thus is proportional to 1-dimensional size of the transformer, instead of an invariable number. As a result, the higher maximal power output of the transformer causes the larger size and the weaker heat-dissipating ability. To solve the heat-dissipating problem, this present disclosure relates to a simple way to upgrade the maximal power output of a microwave power supply such that its heat-dissipating ability and efficiency are as good as before upgrading.